The present invention relates to industrial process control or monitoring systems in which field devices are used to monitor or control an industrial process. More specifically, the present invention relates to wireless process control or monitoring systems.
Process control or monitoring systems are used in industrial processes to monitor or control the operation of the process. Example industrial processes include oil refineries, manufacturing plants, etc. A process variable transmitter is located at a field location and used to measure and transmit a process variable, such as pressure, flow, temperature, etc., to another location such as a central control room. Control field devices are placed in the field and can receive commands from the control room, for example, to control operation of the process. For example a control element can be configured to change the position of a valve, adjust the temperature of a heating element, etc., thereby control a process variable.
Such systems have typically operated using wired connections. One wiring technique is a two-wire process control loop in which the same two wires are used to communicate with the field device as well as provide power to the field device. However, more recently wireless communication techniques have been used to communicate information in process control or monitoring systems. These techniques can include, for example, wireless “mesh network” communication techniques or direct communication links.
It is frequently desirable to diagnose operation of the industrial process. Such diagnostics include, for example, identifying a component of the process which has failed or which is in the process of failing. This allows the failure to be repaired, perhaps before the component ultimately fails, thereby improving reliability and reducing downtime.